package  main.java.leetcode.editor.cn;
//2023-03-08 19:07:01
//定义一个函数，输入一个链表的头节点，反转该链表并输出反转后链表的头节点。 
//
// 
//
// 示例: 
//
// 输入: 1->2->3->4->5->NULL
//输出: 5->4->3->2->1->NULL 
//
// 
//
// 限制： 
//
// 0 <= 节点个数 <= 5000 
//
// 
//
// 注意：本题与主站 206 题相同：https://leetcode-cn.com/problems/reverse-linked-list/ 
// Related Topics 递归 链表 👍 550 👎 0

class FanZhuanLianBiaoLcof {
    public static void main(String[] args) {
        //创建该题目的对象方便调用
        Solution solution = new FanZhuanLianBiaoLcof().new Solution();
    }

    public class ListNode {
        int val;
        ListNode next;
        ListNode(int x) { val = x; }
    }
    //leetcode submit region begin(Prohibit modification and deletion)
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode reverseList(ListNode head) {
//        ListNode pre = null;
//        ListNode cur = head;
//        ListNode node;
//        while (cur != null){
//            node = cur.next;
//            cur.next = pre;
//            pre = cur;
//            cur = node;
//        }
//        return pre;

        if(head == null || head.next == null){
            return head;
        }

        ListNode reverse = reverseList(head.next);
        head.next.next = head;
        head.next = null;

        return reverse;
    }
}
//leetcode submit region end(Prohibit modification and deletion)

}
